1992 Fiscal Year Final Research Report Summary
Diffusionless Transformations and Related Effects of Intermetallic Compounds and Ceramics
| Project/Area Number |
03452246
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical properties of metals
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| Research Institution | Osaka University |
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Principal Investigator |
SABURI Toshio Osaka University Department of Materials Science and Engineering Professor, 工学部, 教授 (40029020)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUDA Takashi Osaka University Department of Materials Science and Engineering Research Associ, 工学部, 助手 (50228912)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Diffusionless transformation / Intermetallic compound / Ti-Ni alloys / Barium titanate / Stronchium-barium niobate / Domain structure / Shape Memory / Ceramics |
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| Research Abstract |
(1)Transformation and self-accommodation machanisms of the R-phase in Ti-Ni-Fe and Ti-Ni-Al shape memory alloys were studied by means of optical and transmission microscope observations. Sequences of transformation events were recorded successfully with video tapes using a TV camera. Through the observation we found the following. The R-phase transformation takes place by nucleation and growth in a heterogeneous manner. Nucleations take place at stress concentrated places, e.g., matrix-inclusion interfaces and dislocations. The R-phase can nucleate from the stress field of a single dislocation. The R-phase self-accommodates during growth. The fundamental unit of the self-accommodation is composed of four variants.
(2) Cu content dependence and effect of thermo-mechanical treatment of shape memory characteristics in Ti-Ni-Cu alloys were investigated by means electrical resistivity measurement, differential scanning carlorimetry, X-ray diffraction and thermal cycling test under constant load. It was found that the maximum recoverable elongation decreases from 3.3% to 2.7%, that the hysteresis also decreases from 30K to 4K with increasing Cu content from0 to 20at.% and that recoverable elongation increases with the thermo-mechanical treatment.
(3)The cubic to tetragonal(paraelectric to ferroelectric) transformation in barium titanate was in investigated by in situ transmission electron microscope observation. It was found that the transformation takes place heterogeneously by nucleation and growth mechanism.
(4)The paraelectric to ferroelectric transformation in strontium barium niobate was investigated by dielectric constant measurement, X-ray diffraction and in situ electron microscope observation. It was found that the transformation is diffuse due to a incommemsurater structure.
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